The conventional way of manufacturing a trailer frame for a trailer for a truck today is to create an I-beam by welding together webs and flanges of the beam that have the dimensions required to achieve the desired strength of the frame. It is common that transverse beams, axle fittings and other components are also welded to the frame. One problem is that welding significantly reduces the fatigue strength of the frame.
EP1997717 discloses a trailer frame in which a sub-base comprises a forward and a rear beam that are joined together by screws.